JPH0131021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic speed governor for a self-igniting internal combustion engine, in particular a PI speed governor having at least a PI operating characteristic or a feedback circuit, The present invention relates to an electronic speed governor for a self-ignition internal combustion engine, which includes a comparison circuit that compares speed and idling rotational speed, and controls the rotational speed of the internal combustion engine according to the rotational speed, fuel supply amount, and position of an accelerator pedal.

[Prior Art] Generally, a speed governor for a self-ignition internal combustion engine must have a function of regulating the rotation speed to a predetermined rotation speed as quickly as possible when the rotation speed fluctuates. Such a function is realized by making the proportional operation characteristic of the speed governor steep, that is, by making its proportional gain large.

For example, an electronic governor is known which has P (proportional), I (integral), and D (differential) operating characteristics and whose proportional gain can be adjusted from 0 to about 10%. For example, Tokko Akira
In the device disclosed in Publication No. 51-3849, the deviation between the actual value and the target value of the rotational speed is input to the PID governor, the target value of the fuel supply amount is formed according to the deviation, and the difference between the actual value and the fuel supply amount is determined. The rotational speed is controlled to the target value by adjusting the fuel supply amount according to the difference. In such devices, a feedback signal is sent to the desired value of rotational speed in accordance with the amount of fuel supplied to change or adjust the desired value of rotational speed, thereby adjusting the proportional operating characteristic. Furthermore, when the rotational speed becomes too high, the rotational speed is limited by limiting the fuel supply amount to a predetermined fuel supply amount.

[Problems to be Solved by the Invention] Such conventional control devices have the drawback of poor dynamic characteristics. For example, if the load suddenly changes or the target value of rotation speed set by the accelerator pedal suddenly changes, the proportional gain will be large, so control will become unstable and the output signal of the governor will not change accordingly. It vibrates,
As a result, the rotational speed fluctuates significantly around its target value, resulting in an unstable operation of the internal combustion engine. In the case of self-igniting internal combustion engines, stability,
Considering that reliability and running characteristics must be good, such instability is undesirable.

In the device described in the above-mentioned Japanese Patent Publication No. 51-3849, when the rotational speed becomes too high, the rotational speed is limited by limiting the amount of fuel supplied to a predetermined amount of fuel determined by the rotational speed. However, it is not possible to prevent the rotational speed from fluctuating around the target value and making the operation of the internal combustion engine unstable.

Furthermore, Japanese Patent Laid-Open No. 54-150519 describes a control device for a self-ignition internal combustion engine that controls the amount of fuel supplied by controlling the position of a control rod of an injection pump according to a target value of the amount of fuel supplied. ing. In the case of this system, the proportional gain is constant, and the target value of the fuel supply amount is calculated by increasing the starting amount at the same time as ensuring that the exhaust gas composition and exhaust gas temperature do not exceed predetermined values. The upper and lower limit values of the input parameters are set using a maximum value selection circuit and a minimum value selection circuit so that the input parameters can be easily determined. In other words, in such devices, the parameters input to the speed governor are limited, but the output signal of the speed governor is not limited, so if the load suddenly fluctuates as described above, If the target value of the rotational speed set by the accelerator pedal suddenly changes, the output signal of the speed governor will also change or oscillate accordingly, resulting in unstable operation of the internal combustion engine. There is a drawback.

Therefore, the present invention solves these conventional drawbacks and provides an electronic control system for a self-ignition internal combustion engine that is capable of stably and safely controlling the rotational speed even if the proportional operating characteristic is quite steep. The purpose is to provide a speed governor.

[Means for solving the problems] According to the present invention, in order to achieve the above object,
In an electronic speed governor for a self-igniting internal combustion engine with a speed governor having a PI operating characteristic that determines the fuel supply amount according to the current rotational speed and the accelerator pedal position, The upper and lower limit characteristic curves SO, SU therefore define the upper and lower limit values of the fuel supply.
Characteristic signal generators 23, 24; 49, 5 that generate
0, and the fuel supply amount obtained by the speed governors 15, 48 according to the current rotational speed and accelerator pedal position is determined by the characteristic signal generator according to the current rotational speed and accelerator pedal position. If the value SO of the upper limit characteristic curve obtained is exceeded,
The fuel supply amount is limited to the value of the upper limit characteristic curve or less, and if it falls below the value SU of the lower limit characteristic curve, the fuel supply amount is increased to the value of the lower limit characteristic curve or more, and the speed governor A configuration is adopted in which the amount of fuel supplied is limited within the range of values determined by the upper and lower limit characteristic curves.

[Function] In such a configuration, the fuel supply amount obtained by the governor according to the current rotational speed and accelerator pedal position is determined by the upper and lower limit characteristics obtained at the current rotational speed and accelerator pedal position. Since the limit is set within the value range determined by the curve, the upper and lower limit values of the governor output signal will be limited even if the load suddenly changes or the target value of rotation speed changes suddenly. This prevents fluctuations or vibrations in the governor output signal that were seen in conventional devices, and as a result, the operation of the internal combustion engine no longer becomes unstable, allowing the engine to run safely and reliably. It becomes possible to drive with good characteristics.

Considering that the characteristic curve is very steep, the output signal of the governor is fed back,
The target value of rotational speed is reduced to prevent too rapid changes from occurring. The feedback characteristics are then determined proportionally or non-linearly.

In this way, the governor according to the invention operates very stably even in the case of very steep characteristic curves and, like a purely mechanical governor, can control such abrupt characteristic curves reliably. This makes it possible to perform good speed regulation. In particular, if the speed regulation is carried out by providing limit characteristic curves adjacent to each static reduction characteristic curve, these limit characteristic curves can be formed relatively easily, and in this respect the invention is particularly preferred. becomes.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows in block diagram form an electronic speed governor for controlling the rotational speed of a self-igniting internal combustion engine such as a diesel engine. 10
indicates an accelerator pedal, the amount of depression thereof is converted into a voltage amount by an angular voltage converter 11, and a signal corresponding to a target value of rotational speed is obtained from the angular voltage converter 11 according to the position of the accelerator pedal 10. After this converter 11, there is a comparison point 12, a maximum value selection circuit 13, a comparison point 14 and a speed governor 15.
The output of the speed governor 15 is connected to a speed governor member 16 which controls the regulating rod of the internal combustion engine 17. The output signal of the speed governor 15 is connected to the negative input of the comparison point 12 via a feedback circuit 18. A target value signal generator 20 for idling rotational speed is provided, and this signal generator 20 is input to a maximum value selection circuit 13, which is a comparison circuit for comparing the idling rotational speed and the target rotational speed. Also, select the maximum value among them and generate it in the output. The rotation speed signal obtained from the rotation speed measuring device 21 is the comparison point 1.
It is input to the minus input of 4.

23 and 24 each indicate a characteristic signal generator;
Its input is connected to the rotational speed measuring device 21 and the converter 11, while its output is connected to comparison circuits 25,26. Furthermore, the output of the speed governor 15 is input to these comparison circuits 25 and 26, respectively. Speed governor 15
The input 27 of can be connected via switches 28, 29 to the outputs of the characteristic signal generators 23, 24, in which case the switches 28, 29 can be controlled by the output signals of the comparison circuits 25, 26, respectively. can.

The operation of the speed governor shown in FIG. 1 is basically already known, and when the accelerator pedal position is determined, the target value of the rotational speed is determined accordingly, and this target value of the rotational speed is determined at the comparison point 12. The output signal of the speed governor 15 is adjusted or changed in accordance with the fuel supply amount. This adjustment is performed by the speed governor 15
When the output signal increases, that is, when the amount of increase in the amount of fuel supplied is large, the target value of the rotational speed is decreased accordingly. Specifically, the larger the amount of increase in the fuel supply amount is, the lower the target value of the rotational speed is. Such adjustments are made to suppress too rapid changes.

The target value of the rotational speed thus adjusted at the comparison point 12 is compared in the maximum value selection circuit 13 with the target value of the idling rotational speed obtained from the signal generator 20. This prevents the internal combustion engine from falling below the idling rotational speed, and when the target value of the rotational speed output from the comparison point 12 becomes smaller than the idling rotational speed, the maximum value selection circuit 13 selects the idling rotational speed. This is done to select the target value of .

The target value of the larger rotational speed selected by the maximum value selection circuit 13 is compared with the current rotational speed obtained from the rotational speed measuring device 21 at a comparison point 14, and the deviation is inputted to the speed governor 15. be done.
The speed governor 15 generates an output signal according to the deviation between the current rotational speed and the target value of the rotational speed determined according to the accelerator pedal position. The output signal of the governor 15 indicates the desired fuel supply QK, and the corresponding fuel supply is supplied to the internal combustion engine 17 via the governor 16 and the regulating rod connected thereto.

The circuit of FIG. 1 is controlled according to the characteristic curve illustrated in FIG. 2a. In the figure, n indicates the rotation speed. When the rotational speed becomes equal to or less than the idling rotational speed nLL, the maximum value selection circuit 13 selects the target value of the idling rotational speed. During idling, the function of the feedback circuit 18 is disabled, so the maximum value selection circuit 13 always selects the idling rotational speed nLL as the target rotational speed value. Therefore, the characteristic curve is a characteristic curve extending perpendicularly to the point nLL, as shown in FIG. 2a. Furthermore, the individual descending (decreasing) characteristic curve can be moved by changing the position of the accelerator pedal FP.

FIG. 2b shows the characteristic of the feedback circuit 18, in which the amount .DELTA.nso11 for reducing the setpoint value of the rotational speed is illustrated with respect to the fuel supply signal QK. When the feedback rate is constant, that is, when the ratio between the output signal and the input signal of the feedback circuit 18 is constant, and as the amount of increase in the amount of fuel supplied increases, the target value of the rotation speed is decreased in proportion to it. , the solid line occurs. If the feedback rate by the feedback circuit 18 is not constant, for example, two characteristics as shown by the dotted line can be selected, and if the fuel supply amount increases to a certain extent, even if the fuel supply amount increases further, the rotation will not continue. It is also possible to make the amount of decrease in the target value of the speed constant, or to greatly increase the amount of decrease in the target value of the rotational speed to obtain a non-linear characteristic.

Figure 3 shows the first curve using a simplified characteristic curve.
A state in which the speed governor 15 shown in the figure is controlled and the control state is changed is illustrated. In the figure, the solid line IR indicates the weight loss characteristic curve for a static, ie, stabilized state. Also, SO shows an upper limit characteristic curve, and
SU exhibits a lower limit characteristic curve. These two limit characteristic curves are decreasing characteristic curves which have a purely proportional characteristic with respect to the signal characteristic.

What is important in the present invention is that when the deviation in fuel supply amount or rotational speed fluctuates in the shaded area, that is, in the area formed by both limit characteristic curves, the output signal of the governor is not limited; On the other hand, the output signal of the governor becomes limited only when the deviation becomes so large that it reaches one of the two limit characteristic curves.

FIG. 3b shows the operating characteristics when the load on the internal combustion engine is reduced, in which the starting point is indicated by operating point 30. Assume that the load changes at the operating point 30, for example, the load decreases.
If the rate at which the load decreases is slow, it will descend along the solid line and the rotational speed will increase, reaching the target point 31 and becoming stable, but if the fluctuation is rapid, the rotational speed will increase and The upper limit characteristic curve SO is reached at point 32, and the rotation speed is controlled to increase as it moves downward along that line, and when the value of QK reaches the target point 31 or less, it leaves the upper limit characteristic curve at point 33, In this way, the target point 31 is finally reached by drawing a spiral. Note that in the figure, nist is the current rotation speed.

In conventional devices, the upper and lower limit characteristic curves SO and SU are not provided, so the rotational speed fluctuates significantly around the target point 31, making the internal combustion engine extremely unstable. In the embodiment of the invention, such instability can be prevented since upper and lower limit characteristic curves SO, SU are provided.

The closer this upper limit characteristic curve is to the starting point, the further the control approaches the target point. Of course, such a control has limits for reasons of stability and control characteristics, and when the two limit characteristic curves overlap, the result is an unstable operating characteristic similar to that of a P governor with a similarly steep characteristic curve.

In order to limit the fuel supply amount to the maximum as described above, the limit characteristic curves SO and SU are changed according to the current rotation speed obtained from the rotation speed measuring device 21 and the position of the accelerator pedal 10 (target rotation speed). It is preferable to do so. For this purpose, the current rotational speed and the accelerator pedal position are respectively input to characteristic signal generators 23, 24 which generate upper and lower limit characteristic curves SO, SU, respectively.

The signal characteristics shown in FIG. 3b for controlling the characteristics are realized by the characteristic signal generators 23, 24 shown in FIG. 1 and the comparison circuits 25, 26 connected therebelow. In the two characteristic signal generators 23, 24, shown as blocks, characteristic curves are shown, along which the control takes place at various rotational speeds.

Characteristic signal generator 23 generates an upper limit characteristic curve SO, while characteristic signal generator 24 generates a lower limit characteristic curve SU. When the output value of the speed governor 15 exceeds one of the output signal values of the characteristic signal generators 23 and 24, both switches 2
8, 29 is closed, so that the output of the associated characteristic signal generator 23 or 24 is connected to the control input of the speed governor 15. In this way, each characteristic value is directly input to the speed governor 15.

An example of a controllable PI governor 15 is illustrated in FIG. The main part is negative feedback amplifier 3
5, and a capacitor 36 and a resistor 3 are included in the negative feedback circuit.
A series circuit consisting of 7 is connected. An input 38 is also connected to the input of the speed governor. The non-inverting input of the amplifier 35 is connected between the drive voltage lines.
It is connected to a voltage dividing point of a voltage divider consisting of two resistors 39 and 40.

Charge of capacitor 36 of speed governor 15 (I component)
can be set or changed intermittently by applying a constant potential to the capacitor 36 for a short period of time. This is done by a power supply 41 which can be controlled via input 27. Unlike a controllable current source, this controllable power source 41 does not change the integral time constant, but rather changes the integral time constant (t→
0), the energy state of the PI governor is changed.

Diesel engines are also controlled by computers to obtain accurate values.
The program is performed according to the flowchart shown in FIG. In the first program step 45 in the figure, a rotational speed target value nso11 is determined from the position of the accelerator pedal FP, and in the following program step 46, the feedback value is subtracted from the output signal of the speed governor. Next, the comparator circuit of FIG. 1, that is, the maximum value selection circuit 13
In step 47, the rotational speed target value and the predetermined idling rotational speed value nLL are compared, and in step 46, if the rotational speed target value becomes smaller, the predetermined idling rotational speed takes priority.

The PI governor 15 shown in FIG. 1 corresponds to program step 48, in which the target value of the fuel supply amount is determined according to the formula QK=Kp.Δn+Ts/Ti.ΣΔn. However, Kp is an arbitrary constant, Δn is the current rotational speed deviation value, Ts is the measurement time, and Ti is the integration time constant.

Subsequently, in steps 49 and 50, upper and lower limit characteristic curves SO, SU are formed, respectively. Next, in judgment step 51, it is determined whether the lower limit characteristic value SU is larger or smaller, and then in step 52, it is judged whether the lower limit characteristic value SU is larger or smaller than the current rotation speed.
Then, the magnitude with respect to the upper limit characteristic value SO is determined, and the desired fuel supply amount QK as described above is determined.
Further, although not shown, other determination steps and program steps perform predetermined control.

The electronic speed governor of such a self-igniting internal combustion engine allows stable control even in the case of very steep characteristic curves. For stability reasons, the integration rate is 1/
Ti (rate of change of controlled variable) must be chosen very small. But this also means that if an operating factor, such as the load on the engine changes suddenly, e.g. by increasing or decreasing the load within a given period of time, the governor state for a given quantity obtained before the change will change to the new operating point. It means to hold it as it is until it is adjusted to the desired value. For example, if the PI speed governor is slow, there is therefore a risk that if the load is reduced, additional fuel will be applied and the permissible rotational speed will be far exceeded.

What is important in the above-described invention is that when the fuel supply amount signal exceeds or falls below the limit characteristic curve, the fuel supply amount is forcibly limited by the limit characteristic curve of the governor. For this reason, the governor according to the present invention allows a faster control speed and at the same time excellent stability.

[Effects of the Invention] As explained above, in the present invention, the amount of fuel supplied by the governor according to the current rotational speed and the accelerator pedal position is equal to the amount of fuel supplied at the current rotational speed and the accelerator pedal position. Since the limit is within the range of values determined by the upper and lower limit characteristic curves, even if the load suddenly changes or the target value of rotation speed changes suddenly, the upper and lower limits of the governor output signal As a result, fluctuations or oscillations in the output signal of the governor, which were observed in conventional devices, are prevented, and as a result, the operation of the internal combustion engine does not become unstable, and the internal combustion engine can be operated safely. Furthermore, it becomes possible to drive the vehicle with high reliability and with good running characteristics.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing a schematic configuration of an electronic speed governor according to the present invention, Figs. 2a and 2b are diagrams explaining the speed regulating characteristics of the present invention, and Figs. 3a and 3b.
The figure is a diagram showing the governor control according to the present invention in more detail, Figure 4 is a circuit diagram showing an example of a controllable PI governor, and Figure 5 explains the operation of the circuit shown in Figure 1. FIG. 10...Accelerator pedal, 11...Angle voltage converter, 13...Comparison circuit (maximum value selection circuit), 1
5... Speed governor, 16... Adjustment member, 17... Internal combustion engine, 18... Feedback circuit, 20... Idling rotational speed target value signal generator, 21...
Rotational speed measuring device, 23, 24...characteristic signal generator, 25, 26...comparison circuit.

Claims (1)

[Scope of Claims] 1. In an electronic speed governor for a self-ignition internal combustion engine equipped with a speed governor having PI operating characteristics that determines the fuel supply amount according to the current rotational speed and the gas pedal position, the gas pedal position 10 and characteristic signal generators 23, 24; 49, 50 which generate upper and lower limit characteristic curves SO, SU which define the upper and lower limit values of the fuel supply according to the current rotational speed 21;
and the fuel supply amount obtained by the speed governor 15, 48 according to the current rotational speed and accelerator pedal position is determined by the characteristic signal generator according to the current rotational speed and accelerator pedal position. If the obtained value SO of the upper limit characteristic curve is exceeded, the fuel supply amount is limited to below the value of the upper limit characteristic curve, and if it falls below the value SU of the lower limit characteristic curve, the fuel supply amount is limited. A self-ignition internal combustion engine, characterized in that the fuel supply amount obtained by the governor is limited to a value not less than the value of the lower limit characteristic curve, and the amount of fuel supplied by the governor is within the range of values determined by the upper and lower limit characteristic curves. electronic speed governor. 2. A maximum value selection circuit 13 is provided for selecting the larger of the target value of rotational speed and the target value of idling rotational speed determined according to the accelerator pedal position,
Claim 1: The fuel supply amount is determined via the speed governor 15 according to the deviation between the rotational speed target value from the maximum value selection circuit and the current rotational speed value.
An electronic speed governor for a self-igniting internal combustion engine as described in 2. 3. According to claim 1 or 2, the target value of the rotation speed is adjusted by feeding back the output signal from the speed governor to the target value of the rotation speed determined according to the position of the accelerator pedal. Electronic speed governor for self-igniting internal combustion engines. 4. The device according to any one of claims 1 to 3, wherein the upper and lower limit characteristic curves are provided adjacent to the characteristic curve that determines the fuel supply amount of the speed governor. Electronic speed governor for ignition type internal combustion engines.